Body Fat Calculator: API and MCP

Body Fat Calculator over REST and MCP: input fields, limits, outputs, one example request and its real answer. Free, no sign-up.

Id: health.body-fat
Version: 1.0.0
Access: Free
Tool page: Body Fat Calculator
Schema: GET /api/v1/tools/health.body-fat

Input

Field	Type	Constraints	Default	Description
`sex` (required)	string	female \| male		Sex
`units`	string	metric \| pounds \| stones	metric	Units
`weight`	number	≥ 20, ≤ 350		Weight (kg)
`height`	number	≥ 120, ≤ 230		Height (cm)
`neck`	number	≥ 20, ≤ 80		Neck circumference (cm) · Just below the larynx, with the tape level.
`waist`	number	≥ 40, ≤ 250		Waist circumference (cm) · Men: at the navel. Women: at the narrowest point. Do not pull your stomach in.
`hip`	number	≥ 50, ≤ 250		Hip circumference (cm) · Measure at the widest point.
`weightSt`	integer	≥ 1, ≤ 55		Weight, stones (st)
`weightLb`	number	≥ 0, ≤ 800		Weight, pounds (lb) · With stones: the pounds over the stones.
`heightFt`	integer	≥ 3, ≤ 8		Height, feet (ft)
`heightIn`	number	≥ 0, ≤ 11.99	0	Height, inches (in)
`neckIn`	number	≥ 4, ≤ 100		Neck circumference (in) · Just below the larynx, with the tape level.
`waistIn`	number	≥ 4, ≤ 100		Waist circumference (in) · Men: at the navel. Women: at the narrowest point. Do not pull your stomach in.
`hipIn`	number	≥ 4, ≤ 100		Hip circumference (in) · Measure at the widest point.

Output

Field	Type	Description
`bodyFat`	number	Body fat (%)
`fatMass`	number	Fat mass (kg)
`leanMass`	number	Lean body mass (kg)
`essential`	boolean	Essential fat level: below 6% for men, 14% for women (ACE).
`athletes`	boolean	Athletes: 6–13% for men, 14–20% for women (ACE).
`fitness`	boolean	Fitness: 14–17% for men, 21–24% for women (ACE).
`average`	boolean	Average: 18–24% for men, 25–31% for women (ACE).
`obese`	boolean	Obese: 25% or more for men, 32% or more for women (ACE).

Example request

curl -X POST https://hesaplayici.com/api/v1/tools/health.body-fat/execute \
  -H 'Content-Type: application/json' \
  -d '{"input":{"sex":"male","units":"metric","weight":80,"height":178,"neck":38,"waist":90,"heightIn":0},"locale":"en"}'

Example answer

{
  "output": {
    "bodyFat": 20.1,
    "fatMass": 16.1,
    "leanMass": 63.9,
    "essential": false,
    "athletes": false,
    "fitness": false,
    "average": true,
    "obese": false
  },
  "steps": [
    {
      "id": "girth",
      "formula": "girth = waist − neck",
      "substitution": "girth = 90 − 38",
      "value": 52,
      "unit": "cm"
    },
    {
      "id": "density",
      "formula": "body density = 1.0324 − 0.19077 × log10(girth) + 0.15456 × log10(height)",
      "substitution": "body density = 1.0324 − 0.19077 × log10(52) + 0.15456 × log10(178)",
      "value": 1.05286
    },
    {
      "id": "bodyFat",
      "formula": "body fat = 495 / body density − 450",
      "substitution": "body fat = 495 / 1.05286 − 450",
      "value": 20.1,
      "unit": "%"
    },
    {
      "id": "fatMass",
      "formula": "fat mass = weight × body fat",
      "substitution": "fat mass = 80 × 20.1%",
      "value": 16.1,
      "unit": "kg"
    },
    {
      "id": "leanMass",
      "formula": "lean mass = weight − fat mass",
      "substitution": "lean mass = 80 − 16.1",
      "value": 63.9,
      "unit": "kg"
    }
  ],
  "notes": [],
  "meta": {
    "toolVersion": "1.0.0",
    "locale": "en"
  },
  "citation": {
    "url": "https://hesaplayici.com/en/health/body-fat-calculator",
    "title": "Body Fat Calculator"
  }
}